Monte Carlo tools to supplement experimental microdosimetric spectra.

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Computational Physics

Background:

• Tissue-equivalent proportional counters (TEPCs) are crucial for experimental microdosimetry, assessing radiation quality in protection and therapy.
• TEPCs use low-pressure gas mixtures to simulate biological targets like the cell nucleus (1-2 µm).
• Monte Carlo (MC) codes can supplement TEPC measurements but often use condensed-history electron transport, neglecting low-energy electrons (<1 keV).

Purpose of the Study:

• To compare experimental microdosimetric spectra from TEPCs with simulations from general-purpose MC codes.
• To evaluate the impact of low-energy electron transport inaccuracies in MC codes on spectral characterization.
• To validate FLUKA and PENELOPE codes against experimental data for accurate microdosimetry simulations.

Main Methods:

• Experimental microdosimetric spectra were acquired using TEPCs with pure propane for (60)Co and (137)Cs radiation at simulated sizes (1.0–3.0 µm).
• Simulated spectra were generated using FLUKA and PENELOPE, which feature detailed electron-photon transport.
• A direct comparison was made between experimental and simulated microdosimetric spectra.

Main Results:

• The study presents a comparison of experimental and simulated microdosimetric spectra.
• Differences in spectral shapes are expected due to the handling of low-energy electron transport in the MC codes.
• The findings highlight potential systematic errors in MC codes that do not fully account for low-energy electron interactions.

Conclusions:

• Accurate simulation of low-energy electron transport is critical for reliable microdosimetry using MC codes.
• Validation of MC codes like FLUKA and PENELOPE against experimental TEPC data is essential for radiation protection and therapy applications.
• This work underscores the importance of detailed electron transport physics in computational dosimetry.